Topic/Presenter: Thermal-Vacuum / Hearty

Question/Comment: 

1)  Baking getter 1 /yr. hard because we would have to open bench.
2)  How about ion pump vs. getter?


Submitted by: Bruce Gillespie


NIC-FPS Response:

There are several options to avoid opening the dewar and baking
(zeolite) getter annually.  First, a charcoal getter would release
water and other adsorbed gases when dewar is rewarmed (and backfilled
with dry nitrogen).  The getter would then be regenerated during the
annual dewar pump-down cycle without requiring opening the dewar.
Second, since zeolite is so efficient at adsorbing and retaining water,
it could simply be regenerated whenever the opportunity presents itself
because the dewar is already opened for another purpose.  This would
still allow use of zeolite which is a much better getter for water
without incurring additional maintenance burdens.  Finally, an ion pump
(of minimal size?say 2.0 l/sec) could be installed to back-up the
getter or replace the getter (sized for say 20 l/sec). A small one to
back-up the getter is an option that may become a necessity if the
annual hold time cannot be achieved.

For now, it seems that the best path is to use a charcoal getter for
long-term operations.  A zeolite getter may be employed during the
early testing phases where the dewar will be repeatedly opened and be
subject to considerable water contamination.  A small ion pump will be
kept as a longer-term option if improvement in hold time is required.


Status: Closed.